Silicon nanowire optical waveguides are used as a platform for photonic components in telecommunications, such as for coherent receivers. Large switch matrices are being considered as an application for this technology but several technical challenges remain in order to achieve a viable product. The challenges include the insertion loss, extinction ratio and closed-loop switch control. Further, germanium photodetectors in the silicon nanowire platform have reached a level of maturity enabling multi-project wafers. This development allows the integration of monitor photodiodes in switch matrices. A combination of a power tap in the output optical path, followed by a waveguide photodiode allows closed-loop operation of a switch cell. However power taps contribute to the insertion loss, which can add up to a significant amount with multiple switch stages. There is a need for an improved 2×1 MMI coupler with lower insertion loss.